On 12/10/93 Id software finally released Version
1 (labeled Version 0.99) of DOOM. The world was never the same. :) By that
time I had seen the 5-22 alpha and the 3 sets of alpha screen shots. I
was under the impression that Doom was going to be a slow and boring game.
Boy was I wrong! I remember practically falling out of my chair when I
tried to get up after playing through the first three levels!

Although minor, there are a number of things
that changed between this version and the current Version 1.9.

Probably the biggest difference is the network
support. Doom 0.99 used network BROADCASTS to communicate. This allowed
other running copies of Doom to display a game being run on another computer.
This was usually used for viewing different angles on 3 different machines
to create a 270 degree view.

(Thanks to Brolin Empey for this screen shot
of Doom V1.1 demonstrating this feature)

Unfortunately using large amounts of broadcasts
could bring a large slow network to a halt. Even worse, all computers on
a LAN must process any received broadcasts, slower computers could crash
if they could not keep up with the number of broadcasts being sent out
by someone playing net-Doom on the same network.

The original version of Doom identified itself
as the "DOOM Operating System". Compared to most other DOS programs of
its time it practically was its own operating system.

There were a number of minor map changes between
V0.99 and V1.9. For one, this swastika shaped trap was altered to look
less like that. (I don't think that it was intended to look like a swastika,
it didn't in the alphas)

There were also several secret areas added
to E1M1 (the ledge over the slime room and later a secret door to the outside
area) and E1M5 (the teleport room). There were also a few other map fixes
to improve deathmatching.

The rendering engine had a few bugs as well.
There is a limit to the number of surfaces it can display at one time so
it does not accidentally get overloaded. Too many surfaces results in a
"hall of mirrors" effect. Obviously this value was set a bit too low, but
was increased later. There was also a bug rendering rooms with high ceilings
that was fixed in V1.666 for use in Doom II (which has lots of high ceilings).